Overexpression of <i>MdNRT2.4</i> Improved Low-Nitrogen Tolerance in Transgenic Tobacco Lines
Apple (<i>Malus domestica</i> Borkh.) is an economically important fruit. The use of nitrate by plants plays a crucial role in their growth and development, and its absorption and dispersal are controlled by nitrate transport proteins (NRTs). In this study, we investigated the potential...
Saved in:
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
|
| Series: | Horticulturae |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2311-7524/11/6/662 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Apple (<i>Malus domestica</i> Borkh.) is an economically important fruit. The use of nitrate by plants plays a crucial role in their growth and development, and its absorption and dispersal are controlled by nitrate transport proteins (NRTs). In this study, we investigated the potential function of <i>MdNRT2.4</i> under low-nitrogen (N) stress by overexpressing it in tobacco. Compared with plants treated with a normal nitrogen level (5 mM), the <i>MdNRT2.4</i> overexpression lines under low-N stress (0.25 mM) exhibited significantly greater plant height and width, as well as larger leaves and a higher leaf density, than wild-type plants, suggesting that the overexpression of <i>MdNRT2.4</i> enhances the low-N tolerance of tobacco. Enhanced antioxidant enzyme activities in the <i>MdNRT2.4</i> overexpression plant lines promoted the scavenging of reactive oxygen species, which reduced damage to their cell membranes. GUS staining of pMdNRT2.4::GUS-transformed <i>Arabidopsis thaliana</i> lines showed that <i>MdNRT2.4</i> was expressed in the roots, vascular bundles, seeds in fruit pods, and young anther sites, suggesting that <i>MdNRT2.4</i> mediates the transport of nitrate to these tissues, indicating that <i>MdNRT2.4</i> might promote nitrate utilization in apple and improve its tolerance to low-N stress. Experiments using yeast one-hybrid and dual-luciferase assays revealed that <i>MdbHLH3</i> binds to the <i>MdNRT2.4</i> promoter and activates its expression. <i>MdbHLH3</i> belongs to the basic helix–loop–helix (bHLH) transcription factor (TF). It is speculated that <i>MdbHLH3</i> may interact with the promoter of <i>MdNRT2.4</i> to regulate N metabolism in plants and enhance their low-N tolerance. This study establishes a theoretical framework for investigating the regulatory mechanisms of low-N responsive molecules in apple, while simultaneously providing valuable genetic resources for molecular breeding programs targeting low-N tolerance. |
|---|---|
| ISSN: | 2311-7524 |